After the capital of the Grand Duchy of Finland was moved from Turku to Helsinki in 1812 the value of Viapori only increased.

British and French naval forces consisting of 77 ships arrayed for the long-expected battle on 6 August 1855.

They formed into a battle line more than 3 km off shore beyond the range of the defenders' obsolete artillery.

The British and French bombarded only the fortress of Viapori and avoided firing at the town of Helsinki directly.

Once the guns had become silenced, the ships remained in the same offshore position, leading to growing fears of a landing.